This invention relates generally to automated systems for transporting materials. More particularly, this invention relates to a dual arm substrate handling robot with a batch loader.
Robots are used in a variety of industrial processes. For example, robots are used to handle substrates in the electronics industry. The term substrate includes such devices as semiconductor wafers, liquid crystal displays, flat panel displays, disk drives, and the like. Substrates are commonly stored in cassettes. In the case of a semiconductor wafer, a cassette of wafers is delivered to a work area. A robotic arm is used to take a single wafer from the cassette and deliver it to a pre-aligner. Once the wafer is pre-aligned, the robotic arm delivers the wafer to a testing apparatus. When testing is completed, the wafer is returned to the original cassette or a different cassette by the robotic arm. While existing robotic arms are acceptable for individual manipulation of substrates in a cassette, they are relatively inefficient for rapidly dispatching a set of substrates from one cassette to another or performing other types of bulk transfer operations.
Thus, it would be highly desirable to provide an improved technique for robotic-based bulk transfers of substrates. Ideally, the bulk transfer technique would be capable of transferring various numerical combinations of substrates to optimize transfer operations. The bulk transfer technique would preferably have a low cost mechanism for determining the number of substrates being transferred at any given time and would adjust the speed of its motion accordingly. Such a device should use known materials and techniques and otherwise be compatible with existing robotic processes.
The apparatus of the invention includes a substrate handling robot with an arm drive mechanism. A first arm is connected to the arm drive mechanism. A multiple substrate batch loader is connected to the first arm. A second arm is also connected to the arm drive mechanism. A single plane end effector is connected to the second arm. The multiple substrate batch loader senses a vacuum signal indicative of how many substrates are held by the multiple substrate batch loader. A vacuum signal interpreter selectively alters the movement of the first arm in response to the substrate load number. An object sensor is connected to the second arm. The object sensor assesses the number of substrates in a cassette adjacent to the multiple substrate batch loader. A substrate loading sequence controller controls the first arm and the second arm in response to the number of substrates in the cassette, such that the second arm removes substrates from the cassette in such a manner as to facilitate complete loading of the multiple substrate batch loader.
The method of the invention includes the step of removing a first substrate from a storage site with a single paddle. A set of substrates are removed from the storage site with a multiple substrate batch loader. A vacuum signal indicative of how many substrates are held by the multiple substrate batch loader is obtained. The motion of the multiple substrate batch loader is altered when the vacuum signal indicates that the multiple substrate batch loader is not fully loaded. The method may also include the step of assessing the number of substrates in the storage site. Individual substrates may be removed from the storage site to facilitate complete loading of the multiple substrate batch loader.
The invention provides an improved technique for robotic-based bulk transfers of substrates. The bulk transfer technique of the invention allows for the transfer of various numerical combinations of substrates to optimize transfer operations. The vacuum sensor associated with the multiple substrate batch loader facilitates a low cost assessment of the number of substrates being transferred at any given time. Based upon this information, the motion of the robot may be altered. Advantageously, the invention utilizes known materials and techniques and is otherwise compatible with existing processes.